The Tina McIntyre actress is quoted by The Sun as saying that the 80-year-old is "still a womaniser".
"I'm not joking, he's always touching me on the bum," Keegan said.
"But because it's Ken Barlow he gets away with it. He's a legend."
Roache revealed that he has slept with up to 1,000 women while featuring on Piers Morgan's Life Stories earlier this year.
The Ken Barlow actor is currently dating 41-year-old weathergirl Emma Jesson.